#include <errno.h>
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
    const char *program_name = argv[0];
    double timeout;

    if (argc < 3)
    {
        fprintf(stderr,
                "setitimer-helper: runs a program with a virtual CPU limit\n"
                "usage: %s TIMEOUT PROGRAM [ARG...]\n"
                "  where TIMEOUT is the virtual CPU limit, in seconds,\n"
                "    and remaining arguments specify the program to run\n"
                "    and its argument.\n",
                program_name);
        return EXIT_FAILURE;
    }

    timeout = strtod(argv[1], NULL);
    if (timeout >= 0.0 && timeout < LONG_MAX)
    {
        struct itimerval it;

        it.it_interval.tv_sec = 0;
        it.it_interval.tv_usec = 0;
        it.it_value.tv_sec = timeout;
        it.it_value.tv_usec = (timeout - floor(timeout)) * 1000000;
        if (setitimer(ITIMER_VIRTUAL, &it, NULL) < 0)
            fprintf(stderr, "%s: setitimer: %s\n",
                    program_name, strerror(errno));
    }
    else
        fprintf(stderr, "%s: invalid timeout value \"%s\"\n",
                program_name, argv[1]);

    execvp(argv[2], &argv[2]);
    fprintf(stderr, "%s: couldn't exec \"%s\": %s\n",
            program_name, argv[2], strerror(errno));
    return EXIT_FAILURE;
}
